A major problem in relation to drug preparation, drug administration or other similar handling of pharmaceuticals is the risk of medical and pharmacological staff being exposed to drugs or solvents which may escape into ambient air. The problem is particularly serious when hazardous drugs such as cytotoxics, antiviral drugs, antibiotics and radiopharmaceuticals are concerned. Other hazards may arise when taking samples relating to virus infections or the like. For these reasons, systems for handling and administrating drugs and other medical substances under improved safety conditions have been developed.
U.S. Pat. No. 4,564,054 (Gustavsson) discloses a fluid transfer device for preventing air contamination when transferring a substance from a first vessel to a second vessel. The device is attached or connectible to the vessel and comprises a first member, in which a piercing member e.g. a needle, provided with a passage is enclosed. The first member has a sealing member e.g. a membrane, through which the needle can be passed. The device further comprises a second chamber, which is detachably connectable to the first member and which also has a sealing member, e.g. a membrane. When the first and second members are connected to each other, the two sealing members are located in a position with respect to each other so that they can be penetrated by the piercing member which is movable with respect to the sealing member.
The sealing members are resilient liquid and gas-proof barriers having the ability of sealing tightly after penetration and retraction of the piercing member to prevent leakage of liquid as well as gas components.
Another example of a device using a barrier member is found in U.S. Pat. No. 3,900,028 in which is disclosed an injection site arrangement for a vessel having a first cylindrical member interposed in a second cylindrical member and a barrier member arranged between the first and second members. During manufacturing of the injection site arrangement, the second member is telescopically inserted into an opening at a lower end of the first member. The barrier member is tightly compressed in the longitudinal direction of the first and second members. The first cylindrical member is thereafter fixed to the second cylindrical member by means of a rib on the first cylindrical member and a corresponding groove an the second cylindrical member. The rib of the first cylindrical member is formed by deformation of the lower edge of the first cylindrical member by subjecting it to heat and pressure during the manufacturing of the injection site arrangement.
The barrier members used in the protective systems are usually made from a resiliently compressible material such as a natural or synthetic rubber or a rubber like material. However, it has been found that medical devices such as those mentioned above have certain limitations.
Resilient barrier members are commonly made from a thermoplastic elastomeric polymer material (TPE) allowing the members to be affixed in a protective injecting device by ultrasonic welding. The ultrasonic welding procedure is temperature dependent and has to be carefully controlled as the manufacturing tolerances are small. Consequently, production of the prior art protective injection devices is complicated and costly. The barrier members are mounted in the protective injecting devices with a predetermined amount of tensioning compression. The amount of tension applied to the barrier member is critical. If the barrier member is too highly tensioned, it may result in the piercing member punching out a piece of the membrane when the membrane is penetrated. On the other hand, if the tensioning of the membrane is too low, the injection site will not close completely after removal of a piercing member. Accordingly, mounting of the resilient barrier members requires a carefully controlled process.
A further problem is that resilient barrier members are subject to aging and may loose some of the production induced tension over time.
It has been suggested in WO 2010/127691 A1 to apply the resilient barrier member between two parts of a protective injection device. A first part of the protective injection device in WO 2010/127691 A1 is a connecting part for connecting the device with a medical appliance such as a vial and the second part is a tensioning part that can be locked in engagement with the first part with the resilient barrier member clamped between the two parts. In the interlocked position of the parts, the resilient barrier member is subjected to a working tensioning force.
The protective injection device in WO 2010/127691 A1 has been found to work very well in diminishing the problems with aging and production tolerances. An objective with the present invention is to offer a further improved protective injection device.